In recent years, as a high-density packing technology, System on Chip (SoC) and System in Package (SiP) are proposed, and a development race is becoming active in view of downsizing, high integration, multifunctionality, low cost, and the like. In these techniques, a plurality of semiconductor chips having different functions constitutes a single package or module. As a joining technique of those chips, there is used, other than a wire bonding method, a technique of interlayer moving wiring such as through vias, bump electrodes, or direct joining of substrates.
In addition, as an packing technology using those techniques of interlayer moving wiring, a three dimensional packing technology which is called Package on Package (PoP) is proposed. In PoP, a wiring board having a semiconductor chip sealed thereon has another wiring board mounted thereon. For example, in one form of PoP, a semiconductor chip is mounted on one of the main surfaces of a substrate of a wiring board; many internal connection electrodes coupled via a coupling substrate are connected to the wiring board to make electrode wirings; and another wiring board is further mounted thereon.
In PoP, as internal connection electrodes, through mold vias are widely used. One form of the through mold via has a structure in which a through hole in a filler-containing resin is filled with conductor. The filler-containing resin is often made to include 80% or more of inorganic filler to make a coefficient of thermal expansion of the resin close to that of an electronic component made of Si. Further, the inorganic filler generally has a permittivity much different from that of the molding resin.
The through mold via formed in the filler-containing resin is connected to the electronic component, and the frequency of a signal passing through the through mold via is 1 GHz or higher. Insertion loss of the signal in that frequency is greatly affected by the permittivity around the through via. The permittivity of the inorganic filler is, for example, approximately 4, and the permittivity of the molding resin is, for example, approximately 3. In this case, since substances having different permittivities exist inhomogeneously in the resin, the insertion loss is increased.